25. Modified Stem of a Plant

This is a picture of a modified stem of a plant. A modified stem of a plant is a specially transformed stem. They transform to perform special functions. This plant's stem was modified for appearance purposes.

24. Pollen

This is a picture of a clover weed. Clover weeds are a pollen and nectar source. Pollen is a powdery substance produced by the male part of a flower, of the anthers of seed plants. Pollen is noticed by humans because it arouses allergic reactions from many people.

23. Ethylene

This is a picture of apples. Apples produce ethylene when ripening. Ethylene is a hydrocarbon gas given off by ripening fruit. Ethylene is what changes the texture and color of fruits when ripening. Other fruits that produce ethylene when ripening are pears and bananas.

22. Exoskeleton

This is a picture of a dragonfly. Dragonflies are an example of an organism with an exoskeleton. An exoskeleton is the outer covering for some invertebrates. It provides support and protection for the organism. Dragonflies, following their larval stage, crack open their exoskeleton to release their abdomen and wings.

21. Frond

This is a picture of a fern. The leaf or leaf-like part of a fern, palm tree, or other similar plant is called a frond. Fronds are usually large, finely divided leaves.

20. Auxin Producing Area of a Plant

This is a picture of a flower with developing buds. Auxin is a hormone most typically found in developing seeds/fruits/buds. Auxin is a plant hormone that regulates plant growth and elongation. It also allows for growth and development of cells in shoots.

19. Basidiomycete

This is a picture of a mushroom. Mushrooms are an example of basidiomycetes. A basidiomycete is a fungus that produces spores on basidium. Basidiomycetes include any subdivision of fungi, which consist of mushrooms, rusts, and puffballs.